A common dumbbell can be purchased in various dimensions of weight that is either fixed or adjustable. Fixed dumbbells are constructed from various solid metal materials to have a specified weight. Adjustable dumbbells are constructed from a short metal bar to which the user can attach various sized solid plate weights. The amount of weight is varied by either selecting a different weight fixed dumbbell or removing and/or adding weight plates to an adjustable dumbbell. For physical exercise, dumbbells are typically grasped by the bar and moved in a large variety of ways to build muscular strength.